Intercomparison of Effective Erythemal Irradiance Measurements from Two Types of Broad‐Band Instruments during June 1995

TLDR

The study examines whether spectral and cosine response mismatches between a multiband and a broadband UVR monitor explain discrepancies in erythemal irradiance measurements. The authors compared daily total biologically effective UVR exposures and dose ratios measured by a multiband and a broadband UVR monitor during varied weather in June 1995. Daily total exposures agreed within about 11 %, while the dose ratio remained ~1.12 from 0900–1700 h and fell to ~0.90 later in the day, indicating time‑dependent discrepancies.

Abstract

The biologically effective global solar ultraviolet radiation (UVR) measurements from a multiband UVR monitor and a conventional broadband UVR monitor are compared. The measurements were performed during the varied weather conditions of June 1995. We compared the daily total exposures measured by both instruments, as well as the ratio of the measured doses throughout the course of each day. The daily total exposures agreed within approximately 11% throughout the month. The ratio between the measured doses held at 1.12 between 0900 and 1700 h (solar zenith angles approximately 16-52 degrees). The ratio decreased from 1.12 to 0.90 during the next 90 min outside that period (solar zenith angles approximately 52-72 degrees) and decreased further beyond that point. Spectral response and cosine response mismatch between the instruments are discussed as the possible cause of discrepancies between the measured doses. Implications for erythemal irradiance monitoring and suggestions for further study are discussed.